Physics - MC

An important user-defined parameter is the Physics Scenario, which specifies the physical models that will be used for the simulation. e.g.

PreInit> /phys/scenario leem
/phys/scenario leem
The registered physics modules are:
       G4EmLivermorePhysics
       Decay

This selects the low-energy electromagnetics physics scenario.

Unlike many other codes Geant4 has a rich selection of physics models. In most cases there are more than two models from which the user can choose for a given physics process. The electromagnetic (EM) physics for example, there are the standard EM (st-EM) processes, which are valid for \(\ge\) 1 keV, and the low-energy EM (le-EM) processes, which are valid down to 250 eV for electrons and gammas. The following table explains what Geant4 physics processes are used for treating the various type of particles in MULASSIS.

Geant4 physics models employed in MULASSIS

Particle

Energy Range of source

Physics Processes

Proton

< 10 GeV

st-EM or le-EM G4Binary

> 10 GeV

st-EM or le-EM G4Binary G4QGSM

Ion

< 10 GeV/n

st-EM or le-EM G4BinaryforLightIons

Neutron

thermal -20MeV

G4Neutron_hp

> 20 MeV

G4Binary + G4QGSM

Electron/Gamma

< 1 keV

le-EM

> 1 keV

st-EM or le-EM

Others

G4LEHEP

The table below is a summary of the physics scenarios defined in MULASSIS. Source in the table is the type of radiation that can be simulated with the selected physics scenario. For example, when dealing with trapped electrons, the user should select “em” or “leem” physics scenario. “hadron+em-ln” can also treat the trapped electrons properly but the inclusion of all the hadron physics is unnecessary and only slows down the simulation.

Warning

The /phys/scenario command is mandatory and it must be issued after the geometry commands and before /run/beamOn.

List of physics scenaris and particles treated in simulation.

Hadron-em-ln

Hadron-em+ln

Hadron+em-ln

Hadron+em+ln

Hadron-leem-ln

Hadron-leem+ln

Hadron+leem-ln

Hadron+leem+ln

Em

Leem

Trapped protons

x

x

x

x

x

x

x

x

Solar protons and light ions

x

x

x

x

x

x

x

x

Cosmic Ray Protons

x

x

x

x

x

x

x

x

Mono-Energeticprotons

x

x

x

x

x

x

x

x

Reactor, fission, D-T, D-D neutron

x

x

x

x

x

x

x

x

Spallation Neutron

x

x

x

x

x

x

x

x

Trapped Electrons

x

x

Mono-Energetic electrons

x

x

X-ray spectra

x

x

Low Energy Neutron

x

x

x

gamma, electron, muon

x

x

x

x

x

x

Low Energy electromagnetics

x

x

x

x

x

Protons

x

x

x

x

x

x

x

x

Anti-Protons

x

x

x

x

x

x

x

x

Neutrons

x

x

x

x

x

x

x

x

Anti-Neutrons

x

x

x

x

x

x

x

x

K+, K-, K0

x

x

x

x

x

x

x

x

Pi+, Pi-, P0

x

x

x

x

x

x

x

x

Light ions

x

x

x

x

x

x

x

x

General ions/nuclei

x

x

x

x

x

x

x

x

Gamma, X-rays

x

x

x

x

x

x

e+, e-

x

x

x

x

x

x

Muon +/-

x

x

x

x

x

x

Mulassis/ml-v02-00/r342